1. Field of the Invention
Substantially large amounts of precious metals such as gold, palladium, rhodium and platinum, as well as copper and zinc, are employed in certain plating baths, drag out solutions and rinses. With the increasing shortages of these metals and their concomitant increases in price, efficient, inexpensive procedures for recovering the metals are desirable. In order for a procedure to be satisfactory, it must have a high efficiency in removing substantially all of the metal ion from the solution, reducing it to metal form. The metal must be produced in a form substantially free of contaminants and readily isolateable. Furthermore, it is desirable to be able to re-use the resulting solution, rather than discarding the relatively expensive chemicals which are employed in the plating, drag out or rinse baths. Therefore, in reducing the metal, it is preferable that the oxidized form of reducing agents that may be employed in the various solutions should also be reduced. Not only should they be reduced, but they should be returned to the solution in a form useful for re-use of the solution.
2. Description of the Prior Art
Metals have been employed, such as iron, zinc and copper, for recovery of the metals noted above. However, iron, zinc and copper do not provide a rejuvenated solution, and the resulting metal salts can be harmful contaminants and pollutants.